Barium promoted iron oxide catalyst suited for use in steam-iron process for producing hydrogen

ABSTRACT

Barium is incorporated with iron oxide to prepare a catalyst or contact mass suited for use in a steam-iron process for producing hydrogen. A process for producing hydrogen using such catalyst is set forth.

United States Patent 1191 Johnston 1 BARIUM PROMOTED IRON OXIDE CATALYST SUITED FOR USE IN STEAM-IRON PROCESS FOR PRODUCING HYDROGEN [75] Inventor: Harlin D. Johnston, Bartlesville,

Okla.

[73] Assignee: Phillips Petroleum Company,

Bartlesville, Okla.

22 Filedz Jan. 24, 1973 [2]] Appl. No.: 326,320

Related US. Application Data [62] Division of Ser. N01 78,566, Oct. 6, 1970, Pat. No,

52 us. (:1. 252/473, 423/658 51] Int. (:1 B0lj 11/22 [58] Field of Search 252/473 Dec. 17, 1974 Primary Eiramiher H. Sneed 7] ABSTRACT Barium is incorporatedwith irOn xide to prepare a catalyst Or contact mass suited for use in a steam-iron process fOr producing hydrogen. A process for producing hydrogen using such catalyst is set forth.

9 Claims, No Drawing s BARIUM PROMOTED IRON OXIDE CATALYST SUITED FOR USE IN STEAM-IRON PROCESS FOR PRODUCING HYDROGEN This is a divisional of application Ser. No. 78,566 filed Oct. 6, 1970, now US. Pat No. 3,726,966.

This invention relates to the production of a catalyst. It also relates to a catalyst useful in the production of hydrogen. In one of its aspects, the invention relates-to the production of a promoted iron oxide catalyst.

In one of its concepts, the invention provides a catalyst or contact mass suitable for use effectively to produce hydrogen from steam which comprises promoting an iron oxide catalyst or contact mass with barium. In another of its concepts, the invention provides a catalyst as herein described in which an iron compound and a barium compound are coprecipitated to provide internally distributed barium within the iron oxide catalyst.

As known, hydrogen is used in a variety of processes for beneficiating hydrocarbonaceous materials, such as petroleum oil, petroleum residua, coal, tar sands, oil shale and the like. Usually, the objective is to convert such materials to liquid hydrocarbons'of certain prop- 2 Other aspects, concepts, objects and several advantages of the invention are apparent from a study of this disclosure and the appended claims.

According to the present invention, there is provided an improved iron oxide catalyst, which is suitable for use in the steam-iron process for production of hydro- I gen, which is prepared by incorporating with iron oxide erties which are required for various uses of .the products. Y

Considerable emphasis has been placed upon,hydrogen production in recent years because of dwindling supplies of crude oil and the likely necessity for converting coal, petroleum residuum; tar sands, or oil shale to liquid hydrocarbons. Such conversions requirecopious volumes of low-cost, relatively purehydrogen which is needed to be generated on location.

A promising route to such hydrogen is the steam-iron process. In this process, a reduced form of iron oxide is oxidized with steam to product hydrogen and then reductive phases of the cycle, and which minimizes the.

amount of iron oxide required to operate such a system. 4 y

l have now discovered a barium-promoted iron oxide catalyst which is highly effective forthe conversion of steam to hydrogen. l have discovered that such a catalyst or a contact mass, particularly as produced by a coprecipitation method is highly effective even upon continued use to produce hydrogen from steam. More specifically, l have discovered, further, that internally distributed barium within such an iron oxide catalyst or contact mass is a highly effective catalyst having a long life even after several oxidative and reductive cycles.

An object of this invention is toproduce a catalyst. It is a further object of this invention to produce a catalyst suitable for improved operation of the stearn-iron oxide process for producing hydrogen. Still another ob ject of the invention is to provide an improved catalyst for the steam-iron oxide process for producing hydro gen by using a particular method from among those available for preparing catalysts or contact masses.

the metal barium. In one modification the catalyst or contact mass is prepared by a-coprecipitation of watersoluble compounds of the barium and the iron following which the coprecipitated compounds areconventionally washed and dried in calcine tov produce a material as described further herein.

The iron oxide of the present invention comprises a major amount of iron oxide (Fe o and a minor amount of barium. The barium isintimately and uniformly distributed throughout the iron oxide and is present in amounts ranging from about 0.2 to about 1.5, preferably from about 0.5 to about 1 weight percent based upon the weight of the total iron oxidecontaining composition, calculated as the metal. Further, the barium-promoted iron oxide composition is of catalytic grade or equivalent; that is, the composition generally and usually is preferably a porous one having a surface area of at least about 1 square meter per gram andshould have a pore volume of at least 0.5 ml/g in pores larger than about 200A.

The barium-promoted iron oxide composition can be prepared by any convenient catalyst or contact mass preparation method which provides an intimate and homogeneous mixture of these two materials. One suit-' ablemethod is by coprecipitatio n in which are used sol uble compounds of iron and barium which are convertedto the oxides on calcination and-which arecoprecipitated such as by the addition of ammonium hydroxide to an aqueous solution containing said compounds. Theprecipitate is then conventionally washed, aged, dried, and calcined to obtain an active iron oxide composition having the desired surface area and pore volume characteristics.

Another method is by preparing an intimate mixture of the mixed oxides of barium and iron. Barium oxide 1 and iron oxide can be intimately blended in a ball mill, for example, or powders of these oxides can be either dry mixed or wet mixed in an aqueous slurry to thoroughly homogenize the mixture. The homogenized mixtures can then be converted into'desired forms such as pellets, agglomerates, extrudates, or other particle shapesusing'conventional catalyst'forming methods.

It has 'been found that the incorporation of barium using the impregnation method is not suitable for producing the improved iron oxide compositions of the present invention. The reason for this is not known with certainty, but it is presently believed that for the barium to be effective, it must be uniformly and internally present virtually in each iron oxide-containing particle. Impregnation methods are believed to deposit the barium substantially only on external surfaces of iron oxide particles.

Barium-promoted iron oxide can be prepared having the desired characteristics of surface area and pore volume .by using conventional catalyst or contact mass preparation methods known in the art. Alternatively, the. barium-promoted iron oxide materials can be treated to increase the number of pores by conventional treatment methods such as steam treatments or by treatment with other agents which can increase the size of the pores, e.g., leaching.

STEAM-IRON PROCESS CONDITIONS The barium-promoted iron oxides of the present invention are utilized in the steam-iron process under conventional conditions; that is, the barium-modified iron oxide is used inthe same manner and under the same conditions as the non-modified iron oxide for the reductive and oxidative portions of the process to produce hydrogen. The improved iron oxide results in a greater converstion rate in each phase of the cycle and thus can significantly reduce the cycle time. Additionally, the barium-promoted iron oxide will remain active for a longer period of time and, thus, iron oxide replacement costs can be reduced.

in general, both the reductive and the oxidative phases of the cycle are carried out at temperatures in the range of from about 1,200 to about 1,700F, preferably from about l,300 to about l,450F. Any convenient pressure can be used such as pressures in the range of from about to about 2,000 psig. Any suitable mode of contact between the iron oxide and the reducing or oxidizing gases can be used, including fixed bed operation, fluidized bed operation, and the like. Aparticularly preferred mode is the free-falling bed wherein particles of the iron oxide are allowed to fall through a reaction chamber while in contact with a countercurrent flow of reaction gases.

The reactive gases in the reductive zone can be any suitable CO- and/or H containing gas streams. Particularly suitable are the CO- and l-l -containing synthesis gas or producer gas streams obtained by suitably reacting heavy carbonaceous fuels with air and steam. The oxidizing gas used in the hydrogen generation zone is preferably steam with few, or no. other components.

The flow rates of the iron oxide and/or the reactive gases within the individual reaction zones will be such.

as to convert a suitable amount of each of these reagents. For example, the iron oxide is not generallyreduced beyond about apercent weight loss, preferably not beyond a 7 percent weight loss because an excessive reduction results in the formation of metallic process comprises hydrogen and steam with perhaps small quantities of hydrogen sulfide. The steam can be condensed and the hydrogen sulfide scrubbed from the stream so as to yield a hydrogen stream of about 99+ percent purity..

EXAMPLE i A number of samples of metal-promotedand unpromoted iron oxides were tested under comparable conditions for the efficiency with which they could be 111- ternatingly reduced with CO and oxidized with steam, the latter operation yielding free hydrogen gas. The procedure was as follows: a porous woven quartz sammetal promoter from a solution of their soluble salts,

ple holder, about 2.5 mm ID by 40 mm long was filled with the 32/65 mesh iron oxide-containing sample; the holder was suspended from a recording balance by a quartz fiber and was positioned in .an electrically heated 1 inch diameter reaction tube; the sample was dried in a nitrogen atmosphere at l292F and weighed; the iron oxide-containing sample was then reduced at l292F in a preheated CO stream flowing at l/hr until a 10 percent weight loss was obtained; the reduction was then halted-and the reduced oxide sample was then subjected to oxidation at l292F by contact with preheated flowing steam until the weight loss had been regained; the steam atmosphere was prepared by passing nitrogen at 8 l/hrthrough a water saturator at 20l -205F and then through the rea'cton'the weight losses and gains during the iron oxide reduction and oxidation stages had previously been shown to closely correspond to CO consumption and H production.

The different iron oxide-containing samples were prepared in various ways. The coprecipitated samples were prepared by precipitating both the iron and the such asthe halides or nitrates, by the addition of precipitating agents such as ammonia, followed by drying and calcining. The impregnated samples were prepared by contacting particles of the solid iron oxide with a solution of a soluble salt of at promoting metal, followed by drying, and calcining. The mixed oxide samples were prepared by intimately mixing, in an aqueous slurry, a mixture of powdered iron oxide and promoter I metal oxide, followed by drying, calcining, and screening to obtain particles containing an intimate mixture of both oxides.

vThe results of the tests showing the suitability of the different iron oxidesamples for use in the steam-iron process are shown in the table. For several of the runs, including the invention runs, the CO consumption rates and the H production rates are shown after both the third and the tenth cycle of operation so that the effect of the promoter'on the effective life of the iron oxide sample can be shown.

Comparing control Run 1 with invention Run 2 in the above-mentioned table shows that intimately associating a minor quantity of barium with the iron oxide results in a dramatic improvement in both the CO consumption (iron oxide reduction) rate and the H production (iron oxide oxidation) rate portions of the cycle. The fact that the surface areas and the pore volumes in pores of 200A are essentially the same further emphasizes that the improvement is 'dueto the presence of the barium promoter.

Comparing invention Run 2 and Run 3 shows'that the manner of barium incorporation into the oxide is critical. When the iron oxide of Run l'was impregnated with barium nitrate. to produce the promotediron oxide of Run 3, an improvement in the conversion rates was obtained. However, the conversion. rates with the impregnated iron oxide declined much faster on continued cycling than with the coprecipitated iron oxide of Run 2.

Runs 4 and 5 show that, in addition to the -presence of promoted amounts of .barium, the iron oxide compois undesirable because it leads to inactivation of the iron oxide and decreases the purity of the hydrogen product.

Runs 7 through 11 show that not all metal oxides have the capacity to promote iron for these reactions. Even magnesium, another alkaline earth group metal, is not effective as an acceptable promoter. Several other metal promoters reduce rather than increase the conversion rates of the iron oxide in this reaction.

In other similar tests, the incorporation of alkaline metals, such as sodium, lithium, and potassium, into the iron oxide was found to give very little improvement in conversion rates and to deposit excessive amounts of carbon on the iron oxide base.

is internally distributed throughout the iron oxide mass of the catalyst. I v

3. A catalyst according to claim 1 wherein the barium is distributed throughout the iron oxide mass by a coprecipitation method including drying and calcining.

4. A catalyst according to claim 1 wherein the barium, calculated as the metal, is from about 0.2 to about 1.5 weight percent of the total weight of the iron oxide containing catalyst composition.

5. A catalyst according to claim 2 wherein the barium, calculated as the metal, is from about 0.2 to about 1.5 weight percent of the total weight of the iron oxide containing catalyst composition.

6. A catalyst according to claim 3 wherein the bar- Steam-lron Process for Hcydrogen Production C tio Ra Consum te H Prodution te Surface Pore r I crease r N I" crease, Run Promoter" Ar e/a, Vo1.ml/g"" Cycle Cycle 70 Cycle Cycle 1 I None 8.1 0.92 179 131 26.8 222 174 21.6 2 0.8% Ba (copreci 9.4 1.0 300 280 6.7 389 378 2.8 3 0.8% Ba (impreg; 258 179 30.6 362 286 21.0 4 1.3% Ba (coprecip.) 0.36 158 175 297 248 16.5 5 0.8% Ba (coprecip) 13.8 0.26 126 116 8.0 185 124 33.0 6 3% Ba (mixed oxide) 87" 181 7 1% Mcg (mixed oxide) 140 98"" 30.0 228 149- 34.7 8 1% C (coprecip) 99 284 9 5% SnO (mixed oxide) 41 145 10 1% MO (coprecip.) 39 74 11 1% CuO (coprecip) 17 71 otes " Excessive carbon deposition.

ln tenns of cc of H, produced per minute per' gr'am of iron oxide-containing sample.

" Promoters calculated in weight per cent based on weight of total Fe o -containing composition.

Reasonable variation and modification as possible ium, calculated as the metal, is from about 0.2 to about within the scope of the foregoing disclosure and the appended claims to the invention, the essence of which is that a barium-promoted iron oxide catalyst or contact mass or steam-iron reduction of hydrogen has been provided, particularly that the barium as incorporated with the iron oxide is herein described by a coprecipitation or equivalent method and that said catalyst is useful in a process for the production of hydrogen by the steam-iron process.

1 claim:

l. A catalyst suitable for use in a steam-iron process for producing hydrogen consisting essentially of iron oxide promoted with a minor amount of barium intimately and uniformly distributed throughout the iron oxide, said catalyst having a surface area of at least about 1 square meter per gram and a pore volume of at least 0.5 ml/gin pores larger than about 200 A.

2 A catalyst according to claim 1 wherein the barium 1.5 weight percent of the total weight of the iron oxide containing catalyst composition.

7. A catalyst suitable for use in asteam-iron process for producing hydrogen consisting essentially of iron oxide promoted with a minor amount of barium intimately and uniformly distributed throughout the iron oxide and wherein the barium is distributed throughout the iron oxide mass by a coprecipitation method including drying and calcining.

8. A catalyst according to claim 7 wherein the barium, calculated'as the metal, is from about 0.2 to about 1.5 weight percent of the total weight of the iron oxidecontaining catalyst composition.

9. A catalyst according to claim 7 wherein the'barium, calculated as the metal, is from about 0.5 to about 

1. A CATALYST SUITABLE FOR USE IN A STEAM-IRON PROCESS FOR PRODUCING HYDROGEN CONSISTING ESSENTIALLY OF IRON OXIDE PROMOTED WITH A MINOR AMOUNT OF BARIUM INTIMATELY AND UNIFORMLY DISTRIBUTED THRUGHOUT THE IRON OXIDE, SAID CATALYST HAVING A SURFACE AREA OF AT LEAST ABOUT 1 SQUARE METER PER GRAM AND A PORE VOLUME OF AT LEAST 0.5 ML/G IN PORES LARGER THAN ABOUT 200 A.
 2. A catalyst according to claim 1 wherein the barium is internally distributed throughout the iron oxide mass of the catalyst.
 3. A catalyst according to claim 1 wherein the barium is distributed throughout the iron oxide mass by a coprecipitation method including drying and calcining.
 4. A catalyst according to claim 1 wherein the barium, calculated as the metal, is from about 0.2 to about 1.5 weight percent of the total weight of the iron oxide containing catalyst composition.
 5. A catalyst according to claim 2 wherein the barium, calculated as the metal, is from about 0.2 to about 1.5 weight percent of the total weight of the iron oxide containing catalyst composition.
 6. A catalyst according to claim 3 wherein the barium, calculated as the metal, is from about 0.2 to about 1.5 weight percent of the total weight of the iron oxide containing catalyst composition.
 7. A catalyst suitable for use in a steam-iron process for producing hydrogen consisting essentially of iron oxide promoted with a minor amount of barium intimately and uniformly distributed throughout the iron oxide and wherein the barium is distributed throughout the iron oxide mass by a coprecipitation method including drying and calcining.
 8. A catalyst according to claim 7 wherein the barium, calculated as the metal, is from about 0.2 to about 1.5 weight percent of the total weight of the iron oxide-containing catalyst composition.
 9. A catalyst according to claim 7 wherein the barium, calculated as the metal, is from about 0.5 to about 1 weight percent of the total weight of the iron oxide-containing catalyst composition. 